Teaching Case

Fall from a height

32-year-old male patient involved in a fall from a 7-m bridge. This deceleration mechnism justified chest CT survey and, consecutive to identifying subcutaneous emphysema and pneumothorax on the latter, bronchoscopy to rule out a tracheo-bronchial injury.

Pneumomediastinum relates to free air collections around mediastinal structures. It is encountered in up to 10% of blunt chest trauma. In over 95% of cases, pneumomediastinum either is associated with a subcutaneous emphysema or results from alveolar rupture. In the remaining cases, pneumomediastinum is induced by lesions of the trachea, bronchi or esophagus. Subcutaneous emphysema is most often associated with rib fractures and sometimes with a pneumothorax. It can extend far away from the chest, to the face, abdomen, scrotum, limbs, mediastinum and retroperitoneum. It may sometimes be responsible for thoracic restriction and ventilatory impairment. Alveolar rupture may result from primary lung trauma or positive-pressure mechanical ventilation. It is followed by centripetal dissection of the released alveolar air through the pulmonary interstitium and along the peribroncho-vascular sheaths into the mediastinum. This pathophysiological process is described as the “Macklin effect”. In the submitted case, pneumomediastinum was associated with subcutaneous emphysema and pneumothorax, all consecutive to rib fractures. Tracheo-bronchoscopy ruled out a tracheo-bronchial injury.